This invention relates in general to photo-fabrication and, more particularly, to a method for treating copper and copper alloys for image reproduction thereon by etching.
Heretofore, for example, in the field of etched circuits developed through photo-fabrication, it has been common practice to apply the so-called photo-resist or photographic emulsion directly upon the copper or copper alloy panel or plate. The particular negative is then positioned and the assembly subjected to a source of light, such as customarily ultraviolet. Upon withdrawal of the negative after light exposure, there is no pattern image or design upon the copper or copper alloy which is visible at such juncture and consequently there is no early or immediate indication of the character of the pattern to be ultimately reproduced so that only upon completion of the subsequent developing and finishing steps can the quality of the reproduced pattern be determined. Thus, the quality of the work to be effected is not capable of rapid determination but necessitates time consuming and costly efforts before the requisite inspection is possible.
Therefore, it is an object of the present invention to treat a copper or copper alloy surface for development thereon of an etched impression with an agent prior to application of the photo-resist whereby immediately consequent upon exposure to a light source the pattern is readily visible, permitting of inspection for determining potential sharpness and fidelity of the ultimate pattern, thereby obviating the necessity of effecting the customary developing techniques before ascertaining the character of the ultimate reproduced pattern.
It is another object of the present invention to provide a method for developing impressions within the field of photofabrication upon copper and copper alloys whereby the same are pre-treated for rapid inspection of the character of the pattern to be ultimately etched thereon.
It is a further object of the present invention to provide a method of the character stated which may be readily practiced by individuals having ordinary skill and training in the art; not requiring departure from techniques heretofore well known.
It is an additional object of the present invention to provide a method of the character stated which obviates the utilization of dies within the photo-resist or photographic emulsion utilized.
It is a still further object of the present invention to provide a method of the character indicated which aids in determining adequate development, that is, removal, of unexposed portions of the photographic emulsion.
It is another object of the present invention to provide a method of the character stated for determining the sufficiency of the removal of the photo-resist and the completeness of the post cleaning of the copper or copper alloy surfaces remaining to constitute the pattern for soldering and/or plating purposes.
It is an additional object of the present invention to provide a method of the character stated which is productive of substantial economies in operation; the use of which brings about a markedly improved product; and which does not require the utilization of costly laboratory apparatus for performance.